1. Field of the Invention
The present invention relates to a magnetic disc unit comprising mechanisms which ensure the loading of a magnetic recording medium such as a floppy disc.
2. Description of the Prior Art
A magnetic disc unit, for instance, a floppy disc unit is an apparatus for magnetic recording or reproducing information on or from a magnetic disc or floppy disc as a magnetic recording medium, and has mainly been used for external storage in computer systems.
The prior art magnetic disc unit has many disadvantages as follows:
FIG. 1 is a side view showing a conventional type of a clamping mechanism of a magnetic disc 71. Here, a center cone 73 as the clamping mechanism is attached to a medium loading arm 74 so that a magnetic disc 71 is stably clamped between the center cone 73 and a spindle 72 as a driving mechanism of the magnetic disc 71. The medium loading arm 74 has a large radius of gyration R so that the center cone 73 is moved linearly in parallel with an axis 72a of the spindle 72 when the magnetic disc 71 is just clamped. By raising and lowering an end 74a of the medium loading arm 74, the magnetic disc 71 is released and clamped, respectively.
Although the conventional clamping mechanism has an advantage that the center cone 73 is stably positioned when clamping, the amount of movement of the end portion 74a of the arm 74 is large, so that the height H of the magnetic disc unit is elongated.
In another conventional type of a clamping mechanism, a shaft is provided just over a spindle so that a center cone is moved along the shaft. While the clamping mechanism has an advantage that the height of the magnetic disc unit can be reduced, the clamping mechanism has disadvantages in that the a clearance between the shaft and the center cone unstably positions the center cone, and that a large pressure is needed when clamping.
In the prior art, the clamping mechanism may sometimes be operated even if the magnetic disc 71 is not inserted perfectly into the magnetic disc unit. This results in damage to the surface 71a of the magnetic disc 71 by the center cone 73. The prior art magnetic disc unit does not have an ejecting mechanism for ejecting the disc 71, so that removal of the magnetic disc 71 is difficult.
FIG. 2 is a side view showing a conventional type of a head loading mechanism having a head loading arm 75 and a solenoid 78 for driving the head loading arm 75. A magnetic head 76 and a sponge pad 77 are provided on the head loading arm 75.
When the head loading arm 75 is pulled down by the solenoid 78 so that the magnetic head 76 contacts the magnetic disc 71, the sponge pad 77 resiliently presses the magnetic disc 71 in such a manner that the vertical vibration of the magnetic disc 71 is restrained. This pad forms a stabilizer mechanism.
However, the pressure of the sponge pad 77 is maximum just after the sponge pad 77 has pressed the magnetic disc 71, and the pressure decreases gradually thereafter. Accordingly, it is difficult to press uniformly and steadily the magnetic disc 71. In addition, at the time of head loading, the operating noise of the solenoid 78 is loud. It is required to provide a link member between the head loading arm 75 and the solenoid 78 for preventing magnetization of the head loading arm 75 by the solenoid 78.